Updates

[nwlandry]

This PR does the following:

• Fixes Rename attr to attrs #15.
• Moves extraneous files related to performance testing, integration testing, and other functionality to _OBS
• Moved all of the files except for the schema and the CHANGELOG out of the schemas folder.
• Made two requirements files: one for unit tests and one for the tutorials.
• Updated the README.
• Moved all of the Jupyter notebooks to the tutorials folder. Made a notebook for each library and an "integration" notebook showcasing the ability to exchange network datasets between libraries.

[nwlandry]

@colltoaction --- are you able to review this?

[colltoaction]

The rest looks good!

[nwlandry]

Thanks so much for the review, @colltoaction! Really appreciate it!